Cancer therapy developed from the 1960s has largely involved the use of surgery, radio therapeutics and chemotherapy. These treatments have shown the effect that the upward curve of cancer death rate soared up to 1973 in the U.S. becomes sluggish. However, surgery and radio therapeutics are topical treatment and so they have limitation that patients are convalescing favorably only when cancer is early blocked as local cancer. Chemotherapy is successful only if all cancer cells are completely eliminated and so chemotherapy may damage the host, normal tissue such as immune system of patients and threaten life of the old and the weak. The main purpose of immuno-therapy is to resist the cancerization by reinforcing immune surveillance. There are several trials as follows.
1) Immunological prevention; An animal of the same class was inoculated with cancer tissue to prevent homologous cancer. For example, viral leukemia of animal may be prevented using its cause virus (Morton et al. 1991, proc. am. assoc. cancer res. 2: 492: 494). However, this method has never been applied to a person and it is difficult to induce cellular immunity.
2) Immunotherapy;
Active Specific Immunization
This immunization is to prevent cancer cells activating specific immune cancer supervisory cells by inoculating patients with self-cancer cells or homologous cancer cells or inactivated self or iso-cancer cells regulated by X-ray irradiation or mitomycin-C. However, this method succeeded in animal experiment not in people. Recently, in order to enhance the expression of specific antigens in cancer tissue, various methods have been of attaching with Con-A or exposing hidden antigens by treating with neuramindase or of forming hybridoma with heterologous cells. However, the use of dendritic cells (Sprinzl et al, Cancer Treat Rev. 2001 August; 27(4): 247-55) or development of other various DNA vaccine treatments (Pantuck et al, Int J Urol. 2001 July; 8(7): S1-4) still have a limit in their safety and effect.
Non-Specific Immunotherapy
This immunization most spotlighted at present is used solely or with chemotherapeutic agents for treating almost all kinds of tumors. The non-specific immunotherapy means that it will not be restricted by kinds of cancer. Although various theories on its mechanism have been suggested, they are on study only it is suggested that the non-specific immunotherapy stimulate reticuloendothelial system specifically activity of lymphocytes. There is Corynebacterium as the chief material actually used in clinical tests. Picibanil (OK-432), which has been used for patients in Korea already, has been studied and produced mainly in Japanese pharmaceutical company. It has been marketed in Japan, Korea or Southeast Asia. Materials formed of Picibanil has been used in treating cancer long before. In 1968, Bush Fehleison et al., Germans, discovered that the progress of cancer ceased or previously existing cancer decreased. In 1891, Coley, surgeon in Chicago, the U.S., made mixed toxin formed of materials extracted from culture medium of streptococci, which was used for many patients.
BCG (or Tubercle Bacillus) and Associated Material Thereof
Living BCG organism: In the 1960s, Old in the U.S. and Mathe in France reported that animal cancer could be cured by inoculating BCG. In 1970, Morton in the U.S. reported that melanoma could also be cured by inoculating BCG. As a result, BCG and its associated materials were broadly used as non-specific immunotherapy. A great amount of BCG inoculation is required to expect increasing immune response. BCG can be inoculated under the skin, directly in cancer tissue region or orally administrated. However, the oral administration of BCG is not effective for people who were inoculated with BCG in their neonatal days but came into contact with tubercle bacillus thereafter (BCG or tubercle bacillus are not absorbed in people having tuberculin positive). In the treatment using living BCG organism, there are side effects such as requiring the great amount of living BCG organism and ulcer around injection, systemic symptom like chill, fever or liver function disorder. However, in case of using the small amount to decrease the side effects, the efficacy is reduced or weak.
Unmethylated CpG DNA
Mammalian DNA is different from bacterial DNA in that they have many CpG inhibitions and cytosine of CpG dinucleotide is selectively methylated. Recently, it has been recognized that CpG motifs in bacterial DNA rapidly stimulated the polyclonal B-cells and so increased IgM secretion, and stopped the progress of cell cycle by anti-IgM antibody and powerfully inhibited the induction of apoptosis to inhibit c-myc expression and made myn, blc2 and bcl-XL mRNA expression increase to protect cells from apoptosis. In other study, it was reported that CpG motifs activated directly B-cells to increase IL-6 and IL-12 secretion within a short time. Clinical test on immune adjuvants and asthmatic treatments using synthesis oligonucleotides including CpG sequences is going in progress the CPG Company in the America.
As described above, although treatments have been developed using diverse immune regulating materials, BCG and CpG among those treatments are just applied to people. Despite broad effects of BCG, it is difficult to apply a great amount of BCG or by blood injection because of its stability. In case of CpG, synthetic oligonucleotides are too expensive.